The present invention relates to a combination of erythrulose in D- or L-form or as the racemate and at least one additional reducing sugar having self-tanning properties and cosmetic compositions containing these for the artificial tanning of the skin. The cosmetic compositions bring about a more even and longer-lasting coloration of the skin and prevent the drying out and uneven peeling thereof compared to known compositions that, for example, contain dihydroxyacetone alone.
Hydroxyketones and hydroxyaldehydes are known active substances for self-tanning agents. The active substances generally processed into creams react with free amino groups of the Stratum corneum and result in brownish-coloured pigments that are bound to proteins of the Stratum corneum. This conversion of reducing sugars with amino acids, peptides or proteins, known as the Maillard reaction, leads to compounds having a carbonyl function that polymerise to brown melanoids.
The hitherto most frequently used active substance is dihydroxyacetone (hereinafter referred to as xe2x80x9cDHAxe2x80x9d). The fast tanning active substance (4-7 hours) does, however, have some disadvantages. The skin colour achieved is yellowish-brown, which produces an unnatural colour, particularly in pale skin. In addition, the tan is irregular and soon pales again because the top-most layers of the epidermis are quickly shed.
It has now been found that a combination of DHAxe2x80x94or another reducing sugar having similar propertiesxe2x80x94with erythrulose does not display the above disadvantages. This may be attributed to the fact that erythrulose dyes the skin more slowly (the colour takes about 20-24 hours to develop) and less intensively, but instead also penetrates lower layers of the Stratum corneum where it is also able to react with the free amino groups. This not only results in more even tanning, but also in a retarded effect, with the result that the tan lasts longer. Moreover the skin becomes less dried out than, for example, with DHA alone. The synergistic effect, that will subsequently also be shown with reference to examples, of the active substance combination erythrulose/other reducing sugars, such as for example DHA, was not predictable.